chown finished partial files earlier

partial files are chowned by the Item baseclass to let the methods work
with them. Now, this baseclass is also responsible for chowning the
files back to root instead of having various deeper levels do this.

The consequence is that all overloaded Failed() methods now call the
Item::Failed base as their first step. The same is done for Done().

The effect is that even in partial files usually don't belong to
_apt anymore, helping sneakernets and reducing possibilities of a bad
method modifying files not belonging to them.

The change is supported by the framework not only supporting being run
as root, but with proper permission management, too, so that privilege
dropping can be tested with them.

1 files changed, 27 insertions, 6 deletions

diff --git a/cmdline/apt-get.cc b/cmdline/apt-get.cc
index e176a3350..b6786faf8 100644
--- a/cmdline/apt-get.cc
+++ b/cmdline/apt-get.cc
@@ -80,6 +80,9 @@
 #include <sys/stat.h>
 #include <sys/wait.h>
 #include <unistd.h>
+#include <pwd.h>
+#include <grp.h>
+
 #include <algorithm>
 #include <fstream>
 #include <iostream>
@@ -659,6 +662,8 @@ static bool DoDownload(CommandLine &CmdL)
 	 Ver != verset.end(); ++Ver, ++i)
    {
       pkgAcquire::Item *I = new pkgAcqArchive(&Fetcher, SrcList, &Recs, *Ver, storefile[i]);
+      if (storefile[i].empty())
+	 continue;
       std::string const filename = cwd + flNotDir(storefile[i]);
       storefile[i].assign(filename);
       I->DestFile.assign(filename);
@@ -1481,7 +1486,10 @@ static bool DownloadChangelog(CacheFile &CacheFile, pkgAcquire &Fetcher,
                           "http://packages.debian.org/changelogs");
    string const path = GetChangelogPath(CacheFile, Ver);
    string changelog_uri;
-   strprintf(changelog_uri, "%s/%s/changelog", server.c_str(), path.c_str());
+   if (APT::String::Endswith(server, "/") == true)
+      strprintf(changelog_uri, "%s%s/changelog", server.c_str(), path.c_str());
+   else
+      strprintf(changelog_uri, "%s/%s/changelog", server.c_str(), path.c_str());
    if (_config->FindB("APT::Get::Print-URIs", false) == true)
    {
       std::cout << '\'' << changelog_uri << '\'' << std::endl;
@@ -1492,7 +1500,7 @@ static bool DownloadChangelog(CacheFile &CacheFile, pkgAcquire &Fetcher,
    string descr;
    strprintf(descr, _("Changelog for %s (%s)"), Pkg.Name(), changelog_uri.c_str());
    // queue it
-   new pkgAcqFile(&Fetcher, changelog_uri, "", 0, descr, Pkg.Name(), "ignored", targetfile);
+   pkgAcquire::Item const * itm = new pkgAcqFile(&Fetcher, changelog_uri, "", 0, descr, Pkg.Name(), "ignored", targetfile);
 
    // Disable drop-privs if "_apt" can not write to the target dir
    CheckDropPrivsMustBeDisabled(Fetcher);
@@ -1500,18 +1508,18 @@ static bool DownloadChangelog(CacheFile &CacheFile, pkgAcquire &Fetcher,
    // try downloading it, if that fails, try third-party-changelogs location
    // FIXME: Fetcher.Run() is "Continue" even if I get a 404?!?
    Fetcher.Run();
-   if (!FileExists(targetfile))
+   if (itm->Status != pkgAcquire::Item::StatDone)
    {
       string third_party_uri;
       if (GuessThirdPartyChangelogUri(CacheFile, Ver, third_party_uri))
       {
          strprintf(descr, _("Changelog for %s (%s)"), Pkg.Name(), third_party_uri.c_str());
-         new pkgAcqFile(&Fetcher, third_party_uri, "", 0, descr, Pkg.Name(), "ignored", targetfile);
+         itm = new pkgAcqFile(&Fetcher, third_party_uri, "", 0, descr, Pkg.Name(), "ignored", targetfile);
          Fetcher.Run();
       }
    }
 
-   if (FileExists(targetfile))
+   if (itm->Status == pkgAcquire::Item::StatDone)
       return true;
 
    // error
@@ -1557,6 +1565,19 @@ static bool DoChangelog(CommandLine &CmdL)
       tmpdir = mkdtemp(tmpname);
       if (tmpdir == NULL)
 	 return _error->Errno("mkdtemp", "mkdtemp failed");
+
+      std::string const SandboxUser = _config->Find("APT::Sandbox::User");
+      if (getuid() == 0 && SandboxUser.empty() == false) // if we aren't root, we can't chown, so don't try it
+      {
+	 struct passwd const * const pw = getpwnam(SandboxUser.c_str());
+	 struct group const * const gr = getgrnam("root");
+	 if (pw != NULL && gr != NULL)
+	 {
+	    // chown the tmp dir directory we use to the sandbox user
+	    if(chown(tmpdir, pw->pw_uid, gr->gr_gid) != 0)
+	       _error->WarningE("DoChangelog", "chown to %s:%s of directory %s failed", SandboxUser.c_str(), "root", tmpdir);
+	 }
+      }
    }
 
    for (APT::VersionList::const_iterator Ver = verset.begin(); 
@@ -1572,7 +1593,7 @@ static bool DoChangelog(CommandLine &CmdL)
       {
          DisplayFileInPager(changelogfile);
          // cleanup temp file
-         unlink(changelogfile.c_str());
+	 unlink(changelogfile.c_str());
       }
    }
    // clenaup tmp dir